As the Time Division-Long Term Evolution (TD-LTE) system and the 5G system are advancing, there is a higher requirement on data transmission, and correspondingly there is a higher requirement on data transmission through optic fibers in a base station responsible of transmitting data in the TD-LTE system or the 5G system.
Generally the requirement on data transmission can be satisfied by increasing the number of optic fibers, but this will greatly increase a cost.
In a mobile communication system, data are generally transmitted by a base station, and an indoor Base Band Unit (BBU) and a Remote Radio Unit (RRU) are responsible for baseband processing and radio frequency processing functions of the base station respectively, where data generally including operation and maintenance data and IQ signals (baseband signals) are transmitted between the BBU and the RRU through an optic fiber, and an interface between them is referred to as an IR interface. At present, generally original data are transmitted between respective base stations, and in the prior art, the data can be compressed through an IR interface so that a large amount of data can be transmitted reliably and efficiently in a limited bandwidth, but the amount of data can only be reduced by a factor of ½ in the existing compression method.
In the TD-LTE system or the 5G system, the largest sampling width of an IQ signal is 16 bits, and in order to transmit an IQ signal through an optic fiber, it shall be 8/10-encoded (8-bit data are converted into 10-bit data for transmission), so the highest air-interface transmission rate of an 8-antenna device in the TD-LTE standard or the 5G standard can be calculated as 9.8304 Gbps in the equation of:30.72M*32 bits*8 antennas*(10/8)=9.8304 Gbps.
A 10G optic fiber will suffice if it is still used in a 4G system, but the TD-LTE system or the 5G system is provided with a 25G optic fiber, and in order to transmit an IQ signal through a 25G optic fiber, it shall be 64/66-encoded (64-bit data are converted into 66-bit data), which is equivalent to three 10G optic fibers, so a 64-antenna 3D-MIMO device in the 5G system shall be provided with three 25G optic fibers to transmit a signal which is not compressed; and if the signal is compressed in the existing method (the amount of data is reduced by a factor of ½), then the device still shall be provided with two 25G optic fibers, and since the requirement on signal transmission still cannot be satisfied using a single 25G optic fiber, data shall be compressed more efficiently so that the requirement on signal transmission still can be satisfied using a single 25G optic fiber.
Accordingly it is desirable to provide a new method for compressing data so as to improve the compression efficiency.